TOKYO, July 19 (Xinhua) -- Japanese Foreign Minister Taro Kono summoned South Korean Ambassador to Japan Nam Gwan Pyo on Friday to lodge a protest over Seoul regarding the arbitration of a wartime labor dispute.

The Japanese side believes Seoul has missed a deadline to establish an arbitration panel to settle the dispute over wartime labor.

Kono told Nam that Seoul refusing to cooperate with the arbitration process was "unfortunate."

Tokyo had given Seoul until midnight on Thursday to respond to its request for an arbitration panel to be set up comprising three countries to deal with the wartime labor row as per a 1965 bilateral pact made between both countries, including how disputes would be settled.

Bilateral tensions have become strained between both sides over the wartime labor dispute.

Tokyo believes Seoul has not cooperated in trying to resolve the row bilaterally, or by the way of the establishment of an arbitration panel involving a third party.

South Korea's top court, meanwhile, has ordered some major Japanese firms to compensate South Korean plaintiffs over forced wartime labor during Japan's 1910-1945 occupation of the Korean Peninsula, with lawyers being allowed to seize the assets of some major Japanese firms.

Japan believes the rulings are not in line with international law and run contrary to the foundation of friendly and cooperative relations between the two neighbors since the 1965 normalization of diplomatic ties.

Japan also thinks the matter of compensation for wartime labor was "finally and completely" resolved under the pact.

Tokyo has claimed that Seoul has been reluctant to show willingness to advance talks on the matter through diplomatic channels, with Seoul seemingly, from Tokyo's perspective, disregarding a prior deadline as well to name a member to an arbitration panel, along with Japan and a third country, and hence has sought outside arbitration on the issue.

In June, South Korea proposed that companies from both countries fund compensation for the plaintiffs, but Japan spurned the proposal for further dialogue on the matter in this direction.